Apparatus and method for processing container ends for controlling dust

ABSTRACT

The invention relates to a method and apparatus for conditioning metal container ends and for removing particles and accumulated dust. The apparatus, in a preferred form, comprises a minimum of two and preferably three shafts, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around the shaft at an outer surface thereof. A drive rotates the shafts about their axes of rotation. The shafts are aligned and positioned to receive therebetween container ends introduced into the apparatus from an entrance and convey them to an exit with the peripheries of the container ends engaged in the grooves of the shafts such that rotation of the shafts causes the grooves to release particles from the peripheries. Associated dust removal equipment then removes the particles so that dust is not generated in downstream equipment for the utilization of the container ends.

BACKGROUND OF THE INVENTION

I. Field of the Invention

This invention relates to the processing of metal container ends used to close metal containers, especially those intended for holding foods or beverages. More particularly, the invention relates to a method and apparatus for processing such container ends to reduce or eliminate dust that otherwise tends to accumulate in container production and manufacturing apparatus.

II. Background Art

Metal containers of the kind intended to hold foods or beverages (e.g. aluminum beverage cans intended to hold soft drinks, beer or the like) are generally made in two parts, i.e. a metal container body having an open end, and a metal closure (referred to as an “end”) designed to close the open end of the metal body. These two parts are generally provided with an intervening sealant or gasket and are then joined at their peripheries, e.g. by being crimped or rolled together, to form a liquid- and gas-tight joint. While the container ends may simply be flat circular disks, they are more commonly provided with raised and contoured or curled peripheral edges that facilitate the joining process, and they may have flat or slightly domed circular central sections provided with integral tabs and score lines for ease of opening.

Metal container bodies and metal container ends are typically coated with a non-metallic material that resists corrosion of the metal and avoids contamination of the contents of the container with the metal of the container body or container end. Such coatings may also have a decorative function. In the past, the material preferred for the coating of container ends was for the most part a polyvinylchloride (PVC) polymer. Today, for various reasons, this material is no longer preferred and newer non-PVC coatings are often employed, e.g. those made of epoxy resins. While such new coating materials are superior to PVC in many ways, they often have the drawback of generating considerable amounts of “coating dust”, i.e. fine particles of loose residual coating, as the container ends are fed through the machinery of the respective container end and container production lines. Metal dust may also be generated when metal slivers become detached from the edges of the container ends during handling, so dust formation has always been a problem, but the problem has been intensified by the use of the new coating materials. To prevent undue dust build-up or contamination of the environment, the resulting dust has to be manually removed from the equipment or cleaned from a variety of locations in the end manufacturing process. It would therefore be desirable to provide a way of removing and handling the dust so that it does not accumulate in and around the production machinery, and possibly contaminate the interior of the container bodies or the joints between the container bodies and container ends.

It would also be desirable to provide apparatus for shaping or conditioning container ends in an effective manner while controlling the production dust during such processes.

Apparatus for treating container ends or other similar articles is known, but not specifically for conditioning or shaping ends used with containers for foods and beverages, and for dealing with dust thereby generated. For example, U.S. Pat. No. 1,545,177 issued on Jul. 7, 1925 to M. E. Widell discloses an apparatus for curling and sizing can ends, and U.S. Pat. No. 4,947,979 issued on Aug. 14, 1990 to Martin et al. relates to apparatus for transferring articles, such as containers, along a processing path.

SUMMARY OF THE EXEMPLARY EMBODIMENTS

One exemplary embodiment of the present invention provides apparatus for processing or treating container ends to remove loose particles therefrom. The apparatus comprises an enclosure (such as a housing) having a hollow interior, at least three shafts positioned at least partially in the interior of the enclosure, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around said shaft at an outer surface thereof, a drive for rotating the shafts about the axes of rotation, an entrance into the enclosure for container ends, an exit from the enclosure for said container ends, and an airflow-generating device communicating with the interior of the enclosure adapted to remove particles from the interior. The shafts are aligned and positioned to receive therebetween a container end introduced into the interior from the entrance with a periphery of the container end engaged in the grooves of the shafts, such that rotation of the shafts causes the grooves to produce particles at the periphery while conveying the can end from said entrance to the exit from the enclosure.

Preferably, a container end separation device is positioned at the entrance to the enclosure. The separation device is adapted to separate a lowermost container end from a stack of container ends to allow the lowermost container end to pass through the entrance into the interior while temporarily restraining other container ends of the stack. The separation device preferably comprises a part-circular rotating blade having an edge that enters a side of the stack above the lowermost container end to separate the lowermost container end from others in the stack, and a gap in the blade that allows the stack to move towards the entrance in a stepwise manner by a distance corresponding to a thickness of one of the container ends.

The apparatus may additionally include at least one brush within the enclosure positioned to contact the periphery of the container end to remove particles therefrom, and/or at least one nozzle communicating with a source of compressed gas and positioned within the enclosure to direct a jet of the compressed gas onto the periphery of the container end.

Optionally, one of the three shafts can be designated a “control shaft” and have a groove pitch, a groove profile, or a rotational speed that differs from those of the other two shafts. This pitch, profile, or rotational speed difference can cause the container ends to tilt as they rotate and pass through the processing device. This tilting action can cause the periphery of the container end to fit at different angles into the profile of the grooves of the shaft profile, thereby imparting different conditioning characteristics to the periphery of the container end.

Another exemplary embodiment provides an apparatus for processing container ends to remove loose particles therefrom. The apparatus comprises a enclosure having a hollow interior; two shafts positioned in the interior of the enclosure, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around the shaft at an outer surface thereof; a drive for rotating the shafts about the axes of rotation; at least one positioning element adapted to contact the container end to maintain the container end in contact with the shafts; an entrance into the enclosure for container ends; an exit from the enclosure for the container ends; and a airflow-generating device communicating with the interior of the enclosure adapted to remove particles from the interior. The shafts and at least one positioning element are aligned and positioned to receive therebetween a container end introduced into the interior from the entrance with a periphery of the container end engaged in the grooves of the shafts, such that rotation of the shafts causes the grooves to produce particles at the periphery while conveying the can end from the entrance to and through the exit from the enclosure.

Yet another exemplary embodiment provides apparatus for processing container ends to remove loose particles therefrom. The apparatus comprises at least three shafts, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around the shaft at an outer surface thereof; and a drive for rotating the shafts about the axes of rotation. The shafts are aligned and positioned to receive therebetween a container end entering the apparatus with a periphery of the container end engaged in the grooves of the shafts, such that rotation of the shafts causes the grooves to produce particles at the periphery while conveying the container end through the apparatus. The apparatus includes a source of gas under pressure and at least one nozzle communicating with the source and positioned to direct a jet of the compressed gas onto the peripheries of the container ends to remove particles as the container ends are conveyed to an outlet of the apparatus by the shafts.

Yet another exemplary embodiment provides apparatus for processing container ends to remove loose particles therefrom. The apparatus comprises at least three shafts, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around the shaft at an outer surface thereof; and a drive for rotating the shafts about the axes of rotation. The shafts are aligned and positioned to receive therebetween a container end entering the apparatus with a periphery of the container end engaged in the grooves of the shafts, such that rotation of the shafts causes the grooves to produce particles at the periphery while conveying the container end through the apparatus. The apparatus includes at least one brush positioned to contact the peripheries of the container ends to remove the particles as the container ends are conveyed by the shafts.

Yet another exemplary embodiment provides a method of treating container ends to remove loose particles therefrom prior to subsequent processing, which method comprises passing container ends having loose particles through an enclosed volume, engaging the container ends with at least one solid moving element, at least at peripheral edges of the container ends, to break off and remove said loose particles within the enclosed volume, removing accumulated particles from the enclosed volume for disposal, and removing the container ends from the enclosed volume for said subsequent processing. The accumulated particles may be removed by passing a current of a gas through the enclosed volume, and the peripheral edges of the container ends may be brushed and/or impinged with a gas jet to remove the loose particles therefrom.

For at least some of the exemplary embodiments, the apparatus and method provides a way of removing loose particles that would otherwise likely break free from the container ends during handling and thereby generate dust. Thus, “loose particles” are parts of the container ends that easily break free due to impacts, collision and friction when passing through apparatus typically used for handling container ends, and may include such things as projecting shards of metals, edges producing during earing, flakes of coating material, and the like. Advantageously, the apparatus is positioned at or near the beginning of a production line intended for handling container ends and forming containers. In fact, the apparatus may advantageously be positioned at several locations, e.g. at down-stackers or the in-feed systems to compound application liners or the in-feeds to the conversion presses. All of the potential dust is therefore generated and removed before it can appear in inconvenient locations.

For convenience, the following description makes particular reference to ends used for closing metal beverage cans, and especially those used for closing aluminum beverage cans. Such container ends are therefore referred to as “beverage can ends” or just “can ends”. It should, of course, be realized that the present invention is not limited to applications involving the use or treatment of only such can ends, and it also applies to those used for producing containers intended or designed to hold other products. As noted, such container ends are now normally coated with a non-PVC plastics or polymer (i.e. non-metallic) coating material. However, the invention includes the treatment of other container ends, e.g. uncoated or PVC-coated metal container ends.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-section of a typical prior art metal beverage can end;

FIGS. 2A and 2B are simplified schematic views of apparatus according to exemplary embodiments of the invention in which can ends of the kind shown in FIG. 1 are depicted as moving downward from an entrance to an exit of the apparatus (it should be noted that the apparatus does not have to be vertically oriented in this way);

FIGS. 3A and 3B are enlargements of cross-sections of parts of grooves of a kind utilized in the apparatus of FIGS. 2A and 2B;

FIG. 4 is a drawing based on a photomicrograph showing an enlargement of periphery of a can end before treatment according to exemplary embodiments of the present invention;

FIG. 5 is a drawing similar to that of FIG. 4, but showing an enlargement of a periphery of a can end after treatment according to an exemplary embodiment of the present invention;

FIG. 6 a top plan view (with equipment removed for clarity) of apparatus according to a further exemplary embodiment;

FIGS. 7 and 8 are vertical cross-sections of the apparatus of FIG. 6.

FIGS. 9A, 9B, 9C and 9D are sketches each showing a plan view and corresponding partial side view of a shaft having a rotating blade for separating can ends from a stack thereof;

FIG. 10 is a partial vertical cross-section showing the separation of can ends according to the device of FIGS. 9A to 9D, the can ends being located in upright positions;

FIG. 11 is a view similar to that of FIG. 10 showing can ends in an overturned position; and

FIG. 12 is a simple schematic diagram showing apparatus according to exemplary embodiments equipped with vacuum and filter devices.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

A typical metal beverage can end 10 is shown in vertical cross-section in FIG. 1 of the accompanying drawings. The can end has a flat or slightly upwardly domed circular central section 11, a gutter-like countersink 12, and an upturned edge 13 provided with an outwardly-extending curled lip or “curl” 14. Exemplary embodiments of the present invention concern the treating of the extreme end or periphery of the curl 14, as indicated by the circular dashed lines 15, or the general shaping or profiling of the can end or curl 14. The term “treating” in this context means mechanical processing (physical contact) to release particles (collectively referred to as dust) by breaking off or abrading parts of the material or coating of the can end. Such processing may involve “conditioning” the can end, which means any one or more of abrading, buffing, polishing, deburring, etc. of the periphery of the curl 14 to remove flakes of coating material or slivers of metal. Such processing may also include “shaping”, which refers to forming or re-sizing of the diameter of the curled lip, pre-curling, final curling, and profiling, etc., during which physical contact is made with the periphery of the curl and particles are released. This is a mechanical process that incidentally releases loose particles or abrades the can ends to thereby generate dust. Conditioning and shaping may be carried out simultaneously, sequentially or alternatively. In general, therefore, the term “treating” includes procedures designed exclusively to generate dust, and procedures that are designed primarily to do other things to the can end but that, incidentally, generate dust during the procedure. A particularly preferred feature of at least some of the exemplary embodiments is first to produce and release particles, and then to contain, handle and dispose of the resulting dust. The potential for dust formation (e.g. from projecting flakes of coating material or loose shards of metal at the can end periphery) is therefore eliminated or significantly reduced in the apparatus at a designated stage of can end processing, and is thus less of a problem during later processing of the can end and can production.

FIG. 2A is a simplified schematic view of one apparatus 18 according to an exemplary embodiment of the invention. The apparatus has a housing 20 made of any suitably stiff material (e.g. metal such as aluminum or steel). In this embodiment, the housing 20 acts as an enclosure defining an enclosed space or volume of air or other gas. The enclosure formed by housing 20 need not be completely air tight (and generally is not because it has entrances and exits as will be described later) but it is sufficiently enclosed to confine a majority of dust formed within the apparatus to the enclosed space or volume. The front wall of the housing has been omitted in the drawing to expose the interior 21 of the housing to view. In the working apparatus, the housing is closed on all sides except for exits and entrances mentioned below. An upper wall 22 of the housing has an entrance 23 for beverage can ends to be conditioned and/or shaped by the apparatus, and a lower wall has an exit 24 for removal of the can ends after conditioning and/or shaping. The entrance 23 and exit 24 for the can ends are mutually aligned, so the can ends pass through the apparatus following a linear path directly between the entrance and the exit. The apparatus also has an entrance 25 for air to enter the interior of the housing and an exit 26 for removal of air. The exit 26 is connected to a vacuum-generating device (not shown in this view, but see FIG. 12 described later) that causes air to flow freely through the interior of the housing. Alternatively, the entrance 25 may be attached to a source of gas under pressure (not shown), e.g. an air blower or fan, to achieve an equivalent free flow of air through the housing. The air flow or current through the housing should be sufficiently rapid to carry away dust as it is being formed. The air flow may also be directed at the position(s) within the housing where dust generation is the most likely.

The interior 21 of the housing is provided with three elongated upright cylindrical shafts 28A, 28B and 28C each formed with a continuous contoured helical groove 30 in its outer surface. For each shaft, the helical groove 30 generally extends completely from one end of the shaft to the other end. The shafts are rotatable about their longitudinal axes and a drive element or motor (not shown in this view) causes the shafts to rotate all in the same direction. The rotation of all of the shafts is synchronized (or “timed”) to ensure that the helical grooves of each shaft are properly lined up to receive a can end which becomes “wedged in” between the three rotating shafts in the manner shown and described below. The ends of the shafts 28A, 28B and 28C are positioned at the apices of imaginary isosceles triangles centered on the entrance 23 and exit 24 and hence they “surround” the entrance and exit with equal degrees of arc and spacing between the shafts. The shafts are spaced apart sufficiently, and the pitches of the grooves are sufficiently shallow, that a can end 10 entering the housing 20 through the entrance 23 engages in the grooves 30 of each shaft 28A, 28B and 28C and is thereby supported by the grooves and guided to the exit 24 upon rotation of the shafts 28A, 28B and 28C around their longitudinal axes, whereupon the can end 10 eventually emerges from the housing and may be conveyed to further apparatus (not shown) for additional processing. In effect, the curl 14 of the can end 10 enters the groove of each shaft and is thus supported at three positions spaced equally around the periphery of the can end 10. Owing to friction, the can end 10 is caused to rotate about its own central axis as the shafts rotate, so different parts of the periphery of the can end enter the grooves as the can end is transported towards the exit 24. For conditioning, the grooves have cross-sections that substantially or exactly match the outer profiles of the curl 14 and they generate rubbing or friction as the curl enters and passes through the grooves. This causes loose flakes or shards of coating material, or loose slivers or burs of metal, to detach from the can end so that they are no longer present for potential dust formation during later stages of processing. For shaping, the grooves may have a different profile from the curl 14 to cause deformation of the can end or lip, or the shafts may be so close together than they form or compress the curl between them to reduce the diameter of the can end 10. In this operation, too, flakes and shards may be removed to cause dust formation.

FIG. 2A shows a single can end 10 descending through the apparatus between the shafts 28A, 28B and 28C, but several such container ends may be passing through the apparatus at the same time with a degree of separation dictated by the feed-in apparatus (not shown in this view) and the pitch of the grooves 30. However, container ends may be treated singly, if desired.

The dust generated by the contact and friction with the sides of the grooves within the interior of the housing 20 is removed in this embodiment by the stream of air flowing through the interior from the air inlet 25 to the air outlet 26 and may be filtered from the air, collected and discarded using conventional filters or dust-collection apparatus (e.g. cyclones or electrostatic dust separators) located outside the apparatus (not shown in this view, but see FIG. 12). In consequence, the dust does not have an opportunity to settle and build up in the interior of the housing 20 and is quickly removed from the vicinity of the can ends 10.

FIG. 3A shows a profile of one of the grooves 30 on an enlarged scale, and also shows the curl 14 of a can end 10 that fits horizontally into the groove 30. As noted above, for conditioning, the profile of the groove is shaped to substantially match the profile of the curl so that the curl is snugly received within the groove. The groove may also be provided with a roughened surface 32 positioned to remove flakes of coating material from the extreme outer edge 16 of the curl 14 (where the formation of loose flakes and slivers is most likely). The roughened surface may just be a part of the surface of the groove that is no different than other parts, but is preferably specially treated, e.g. by being roughened mechanically or coated with an abrasive material, e.g. by spraying with a carbide powder. Alternatively, the roughened surface 32 may have been subjected to a “vapor honed treatment” to generate different surface characteristics with respect to other parts of the profile of the groove 30. The treatments described above would allow for more or less aggressive curl conditioning characteristics with respect to abrading, polishing or buffing the outer edge of the can end. The shafts 28 themselves may be made of a hard inflexible material having good wear characteristics, e.g. hardened steel.

The apparatus may be designed to accepted different standard can end and food end diameters including the latest “super-end type” profiles and diameters.

FIG. 2B shows an apparatus very similar to FIG. 2A but one of the shafts 28A has been designed as a “control shaft” and has a different groove pitch (spacing between the grooves) than the other shafts 28B and 28C over part “P” of its length as can be seen from the drawing. This causes the can ends to tilt downwardly at the part supported by shaft 28A as the can end moves through this part of the apparatus (as represented by can end 10′). FIG. 2B shows two can ends 10 and 10′ passing through the apparatus. These may actually be separate can ends or, alternatively, the same can end merely shown in two positions as it descends through the apparatus. As shown in FIG. 3B, the downward tilt of the can end in region “P” causes a slightly different part of the outer edge 16 to contact the surface 32 than is the case for the horizontal positioning of the can end 10 at a higher position in the apparatus (e.g. as shown by FIG. 3A). This may be advantageous as it may make it possible to remove flakes of coating or shards of metal that stick to slightly different points around the edge 16 of the can end, so a more effective removal of flakes or shards may be achieved. Of course, it would also be possible to provide a second region (not shown) in which the pitch of the groove in the control shaft were reduced relative to the other shafts (thereby tilting the can end up) so that an even greater region of the outer edge 16 would be subjected to conditioning by the surface 32. Thus, the pitch of the groove of shaft 28A may be varied along the length of the shaft so that a can end 10, during its complete passage through the apparatus, may be tilted to different extents, e.g. from the horizontal to an upward tilt, back to the horizontal and then to a downward tilt. This would ensures that as much as possible of the edge 16 comes into contact with the contact surface 32. If necessary, the profile of the grooves 30 of the other shafts (28B and 28C) may be made more open at the top (as shown in FIG. 3B) to accommodate such tilting if the curl 14 would otherwise bind in the groove when such tilting were carried out. Likewise, the profile of the various parts of the groove in the control shaft 28A should be varied as required to accommodate the tilting and thereby avoid binding.

An equivalent tilting effect may be created in the apparatus of FIG. 2A even without varying the pitch of the grooves, e.g. by rotating one shaft (the “control shaft” e.g. 28A) at a greater or lesser speed than the others, at least for part of the time that a can end passes between the shafts. As an example, the rotational speed of all shafts may be the same as the can end passes through an upper stretch “Q” of the path to keep the can end horizontal, the speed of one shaft might then be increased or decreased as the can end passes through a central stretch “R” of the path to cause tilting, and then the speed might be adjusted in a final stretch “S” to bring the can end once again into the horizontal position ready for removal from the apparatus. If necessary, the variation of speed may be controlled by automatic means, e.g. computer acting on one or more motors used for rotation of the shafts.

A variation of the rotational speed of the shafts may also be used to increase the conditioning effect of the apparatus. As noted above, the can end is caused to rotate by friction with the sides of the grooves in the rotating shafts. If one shaft is rotating faster or slower than the other two (or if all three shafts are rotating at slightly different speeds), the curl of the can end is caused to slip within the groove of one or more of the shafts. This increases friction between the groove and the can end, and thereby the abrasion or polishing effect at the extreme outer edge 16 of the curl 14. Again, this speed difference may be provided during the entire time the can end passes through the apparatus, or it may be commenced or varied at one or more particular positions as the can end passes between the shafts.

As a further alternative, the profile, depth and/or degree of abrasiveness of the contact surface 32 may be made different in different parts of the grooves, e.g. in stretches “Q”, “R” and “S” of FIG. 2A. Thus, shaping (for example) may be carried out in stretch “Q” by causing the grooves to deform or compact the curl 14, the shape and depth of the grooves may then be made suitable for conditioning in stretches “R” and “S”, but with differences of abrasiveness of the contact surface 32 in these stretches so that buffing is carried out in stretch “R” (aggressive abrasion) and polishing in stretch “S” (less aggressive abrasion). This arrangement may also be combined with tilting or speed differentials, if desired.

FIGS. 4 and 5 are drawings made from magnified photomicrographs of the outer edge 16 of a can end before (FIG. 4) and after (FIG. 5) passing through an apparatus according to an exemplary embodiment of the present invention. In FIG. 4, the large arrow points to a shard of coating material overhanging the outer edge 16 of the can end. In FIG. 5, it can be seen that this shard has been removed by contact with the sides of the grooves and particularly the buffing surface 32. The double-headed arrow in FIG. 5 represents and increased region of the outer edge that may be treated by tilting the can end up and/or down during processing.

Clearly, the can end 10 is moved down through the apparatus of FIG. 2A or 2B at a speed related to the average rate of rotation of the shafts 28A, 28B and 28C. The speed should preferably be made as fast as possible to maximize the throughput of the apparatus, and preferably to closely match the transfer or input of can ends from upstream can end process machines, but not so fast that the reliability of the procedure is compromised. As already noted, the apparatus may treat several container ends at the same time to further increase throughput speeds.

FIGS. 6 through 8 show an alternative exemplary embodiment. FIG. 6 is a plan view of the apparatus with an upper wall removed, and FIGS. 7 and 8 are vertical cross-sections taken along the lines VII and VIII of FIG. 6. As in the previous embodiment, the apparatus includes a housing 20 (acting as an enclosure for containing dust within the apparatus) containing three shafts 28A, 28B and 28C each having a helical groove 30. The shafts are mounted on spindles 40 that extend through the upper wall 22 of the housing, and the upper ends of the spindles are provided with pulleys 43 driven in unison by a common drive and timing belt 44. The belt in turn passes around a pulley 45 driven by an electric motor 46 mounted beneath a top plate 47. The motor drives the pulley 45, which drives the belt 44 and causes the pulleys 43 and shafts 28A, 28B and 28C to rotate at the same speed and in the same direction. Optionally, if a speed differential or end tilting effect (as described in a previous embodiment) is desired, one or more of the pulleys may be sized differently from the others. The upper wall 22 has an entrance 23 sized to receive can ends in the form of a stack 50. The stack is supported and guided to the opening by three fixed posts 51 mounted on the upper wall and arranged at equal intervals around the entrance. At the entrance 23, individual can ends 10 are removed from the bottom of the stack 50 and the separated can ends descend in vertically spaced relationship through the apparatus. The separation of individual can ends from the stack is achieved by apparatus shown and described in more detail later. As the can ends descend through the apparatus between the three grooved shafts 28A, 28B and 28C, the outer curls are conditioned in the manner of the previous exemplary embodiment. An outlet tube 52 is provided between the lower ends of the shafts 28A, 28B and 28C and this tube extends through a lower wall 53 of the housing. The lower wall 53 also has an exit 26 connected to a vacuum-generating apparatus (not shown) to remove air and dust from the interior of the apparatus.

This embodiment differs from the previous one in that it does not have an entrance for air in the wall of the housing, but is provided with three groups of vertically stacked gas injection nozzles 55 that blow air or other gas directly onto and over the can ends 10 as they descend through the apparatus. For this purpose, the nozzles 55 are connected to a source of gas under pressure (not shown). The jets of gas dislodge dust and particles from the can ends and generate an airflow that sweeps the dust from the interior 21 of the housing and through the exit 26. Any remaining particles or dust adhering to the edges of the can ends are removed by fixed (non-rotatable) vertically mounted cylindrical brushes 56 that brush the peripheries of the can ends as they rotate and descend through the apparatus. Alternatively, the brushes 56 may be rotatably mounted and driven by a motor (not shown) in a direction opposite to the direction of rotation of the can ends, thereby achieving and even more effective brushing effect. As will be appreciated, the apparatus of FIGS. 6 to 8 generally functions in a manner similar to that of FIG. 2 but with improved dust removal and feed control of the can ends.

As an alternative, the direction of air flow in this apparatus may be reversed. In such a case, the nozzles 55 are connected to a vacuum-generating device to remove air and dust from the vicinity of the can ends 10. Air then enters the housing 20 via exit 26. This arrangement has the advantage that dust is removed from the apparatus at the exact positions where it is formed, but the narrow nozzles 55 may become blocked with large flakes or shards of material. If so, the direction of air flow may be temporarily reversed.

It should be said that, if the apparatus of FIGS. 6 to 8 is positioned in an environment where the production of dust is not a particular problem, e.g. in an location kept isolated from other apparatus used for the formation of can ends or finished cans, the housing 20 may be eliminated because the location itself acts as an enclosure confining an enclosed volume or space for the removal and treatment of dust. The gas jets 55 and brushes 56 (either of which or both may be present) would still have the effect of removing dust from the can ends, but the dust thereby generated would not be specifically contained and would enter the atmosphere (volume) surrounding the apparatus. As noted, in certain environments, this would not case a particular problem, but it would not be preferred for most applications.

In the previous exemplary embodiments, the shafts have been positioned entirely within the enclosure formed by the housing 20. This is not always necessary. For example, referring to FIGS. 7 and 8, the upper end of the outlet tube 52 may be extended to the top wall 22 of the housing and provided with three longitudinal slots dimensioned to allow the inner sides only of the shafts 28A, 28B, 28C to project into the interior of the tube 52 from the sides thereof. Preferably, the slots would be dimensioned to create only a small gap between the outer surface of each shaft and the periphery of its respective slot, thereby permitting only a minimum of air flow from the interior of the tube through the slot. In such a case, the extended tube 52 would then form an enclosure for containment of dust and the remainder of the interior of the housing 20 would be kept relatively dust-free. The shafts 28A, 28B, 28C would then be positioned only partially within the enclosure formed by the tube 52 with the remainder of the shafts outside the tube but still within the housing 20. The tube would be provided with means whereby a flow of gas could be created around the can ends 10 to carry away the dust. For examples, the tube 52 wall of tube 52 might be provided with corresponding holes for the nozzles 55 and a hole or slot below the level of the lowermost nozzle 55 to allow air to escape into the interior of the housing 20 and then through the exit 26. Alternatively, the exit 26 may be connected directly to such a slot via a conduit to prevent dust-laden air from entering the interior of the housing 20. Such an arrangement has an advantage that dust is kept away from moving parts within the housing 20 (e.g. spindles 40) to avoid damage to such parts. Of course, the housing 20 need not then be totally closed and sidewalls could be made open for easier access and maintenance.

FIGS. 9A to 9D illustrate a device 70 for separating individual can ends from the stack 50 at the entrance 23 to the housing 20 (as shown in the previous figures). There may be three of these closely timed separating devices 70 which are attached to the top of each shaft 28A, 28B and 28C. Each of FIGS. 9A to 9D shows a top plan view and a corresponding side view (top end only) of one of the shafts 28A, 28B or 28C (referred to commonly as 28 in these views). Each shaft is provided, at is top end 57, with a part-circular blade 60 having a helical pitch. The blade is only part circular because it has a gap 61 at one region of its periphery. When this gap is positioned away from the entrance 23 of the housing, the bottom can end of the stack 50 is supported by the top edge of the blade 60. As the shaft 28 and the attached blade 60 rotates to position the gap 61 adjacent to the entrance 23 of the housing, the stack drops down so that the bottom can end 10 rests on the upper end of the shaft 28. As the shaft and blade continues to rotate so that the gap 61 moves past the entrance 23, the blade cuts into the stack immediately above the lowermost can end, thereby again providing support for the stack on the blade. The lowermost can end 10 then enters the groove 30 in the shaft and starts its descent through the apparatus while the remaining can ends in the stack 50 are held back for a further full rotation of the shaft. This is shown more clearly in the partial side view of FIG. 10. In this way, the can ends 10 are separated from each other and descend through the apparatus in spaced relationship as shown in FIGS. 7 and 8. As the can ends exit the helical grooves 30 at the bottom ends of the shafts 28, they are no longer supported and they simply fall through the outlet tube 52 and emerge from the apparatus.

While the can ends 10 have been shown in an upright position in the figures above (i.e. the position in which they are installed on upright can bodies), they could equally be fed through the apparatus in an inverted condition as shown in FIG. 11. This may position the can ends in a proper orientation for further processing in some circumstances, e.g. when the can ends are conditioned before the application of a joint sealant because the sealant is applied to the undersides of the can ends. Alternatively, the conditioning apparatus may be positioned after the application of sealant, and prior to the conversion step where the tab and score are installed, in which case the can ends may pass through the apparatus in an upright condition as shown in FIG. 10.

FIG. 12 is a simple diagram showing an embodiment of apparatus 18 (e.g. as shown in FIG. 2) having an air inlet 25 and an air outlet 26. The outlet 26 is connected to a conduit 80 leading to a replaceable filter element 81 which in turn is connected via conduit 82 to a vacuum-generating device 83 (e.g. an electrical air pump). Air exhausted from the device 83 is passed through conduit 84 leading to inlet 26 of the apparatus 18. Consequently, air flows continuously through the indicated circuit and dust removed from the apparatus 18 by the air flow is filtered through filter element 81 where it remains trapped. Once the filter element 81 is fully loaded with dust, it may be replaced or recycled after cleaning in a manner known to persons skilled in the art. In this way, the can ends 10 treated in the apparatus 18 are treated to remove particles of coating and shards of metal, thus generating dust in the confined environment of the apparatus, and then the dust is removed and disposed of in a manner that avoids contamination of other apparatus with the dust.

The embodiments previously described have been provided with three grooved shafts 28A, 28B and 28C. It will be readily appreciated that more than three such shafts may be provided, if desired. Subject to space constraints, any number of grooved shafts may be positioned between the inlet and outlet of the apparatus, thereby providing more points of support for the can ends and increased groove surfaces for conditioning or shaping. In general, however, the advantage achieved by providing more than three shafts is not great. As a further alternative, it is also possible to provide less than three grooved shafts, e.g. two. In such a case, one of the three grooved shafts would be replaced by a fixed post or non-grooved roller positioned just to engage the outer periphery of the can end without causing any shaping or conditioning. Such a post or roller would be provided just to prevent the can end from disengaging with the grooved rollers, i.e. it would be provided merely for positioning support. In such an apparatus, the grooved rollers may be positioned diametrically opposite to each other, with a pair of diametrically positioned fixed shafts or rollers arranged at right angles to the grooved rollers. That is to say, when looking down on the path of the can ends, there would be a grooved shaft, a fixed shaft, a grooved shaft and a fixed shaft at the successive 90 degree positions around the path. While such an arrangement might by advantageous for some situations, an apparatus having three grooved shafts as described is generally preferred.

Ideally, the apparatus of the exemplary embodiments is provided in a can end production line after the station where the overall lid shape is formed (including the peripheral countersink, but excluding the tab and score), the shell press, and before the next station (the “liner”) where the sealant is applied to the inside of the curl. Conditioning the can end at this point prevents residual dust from becoming entrained in the sealant compound, potentially leading to the formation of a leaking can.

The following table provides optional working and more preferred values for apparatus of the kind shown in FIGS. 6 to 8. These values are not essential and are provided merely to illustrate one preferred form of the invention.

TABLE Parameter Working Preferred Vacuum Out  5-800 cfm 200-400 cfm Air In  1-500 psi  10-100 psi Speed of shafts 25-1500 rpm 200-800 rpm 

1. Apparatus for treating container ends to remove loose particles therefrom, comprising: an enclosure having a hollow interior; at least three shafts positioned at least partially in the interior of the enclosure, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around said shaft at an outer surface thereof; a drive for rotating said shafts about said axes of rotation; an entrance into the enclosure for container ends; an exit from the enclosure for said container ends; and a airflow-generating device communicating with said interior of the enclosure adapted to remove particles from said interior; said shafts being aligned and positioned to receive therebetween a container end introduced into said interior from said entrance with a periphery of said container end engaged in said grooves of said shafts, such that rotation of said shafts causes said grooves to produce particles at said periphery while conveying said can end from said entrance to said exit from the enclosure.
 2. The apparatus of claim 1, wherein a separation device is positioned at said entrance, said separation device being adapted to separate a lowermost container end from a stack of container ends to allow said lowermost container end to pass through said entrance into said interior while temporarily restraining other container ends of said stack.
 3. The apparatus of claim 2, wherein said separation device comprises a part-circular rotating blade having an edge that enters a side of said stack above said lowermost container end to separate said lowermost can end from others of said stack, and a gap in said blade that allows said stack to move towards said entrance in a stepwise manner by a distance corresponding to a thickness of one of said container ends.
 4. The apparatus of claim 1, having at least one brush within said enclosure positioned to contact said periphery of said container ends to remove particles therefrom as said ends proceed from said entrance to said exit of the enclosure.
 5. The apparatus of claim 1, comprising a source of gas under pressure and at least one nozzle communicating with said source and positioned within said enclosure to direct a jet of said compressed gas onto said peripheries of said container ends as said container ends proceed from said entrance to said exit of the enclosure.
 6. The apparatus of claim 1, wherein said groove of one of said at least three shafts has a pitch that differs from said grooves of others of said at least three shafts at least over a part of said surface of said one shaft.
 7. The apparatus of claim 1, wherein said drive is adapted to rotate one of said shafts at a different speed of rotation than other of said shafts, at least for part of a period of time during which a container end passes from said entrance to said exit of the enclosure.
 8. The apparatus of claim 1, wherein at least one of said grooves has a surface treatment along part of its length adapted to modify friction at a position where said container end engages with said groove.
 9. The apparatus of claim 8, wherein said surface treatment has different at least two sections along said length and said sections differ from each other in surface abrasiveness.
 10. The apparatus of claim 1, wherein said groove of at least one of said shafts has a profile modified to accommodate tilting of said container end within said groove along part of its length.
 11. The apparatus of claim 1, wherein at least part of said groove of at least one shaft is adapted to condition said periphery of said container end.
 12. The apparatus of claim 1, wherein at least part of said groove of at least one of said shafts is adapted to shape said periphery of said container end.
 13. The apparatus of claim 1, wherein said grooves of said shafts are adapted to condition and shape said periphery of said container end.
 14. The apparatus of claim 1, wherein at least part of said groove of at least one of said shafts is adapted to remove particles of coating from a perhiphery of a container end having a non-metallic coating provided thereon.
 15. Apparatus for treating container ends to remove loose particles therefrom, comprising: a enclosure having a hollow interior; two shafts positioned at least partially in the interior of the enclosure, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around said shaft at an outer surface thereof; a drive for rotating said shafts about said axes of rotation; at least one positioning element adapted to contact said container end to maintain said container end in contact with said shafts, an entrance into the enclosure for container ends; an exit from the enclosure for said container ends; and a airflow-generating device communicating with said interior of the enclosure adapted to remove particles from said interior; said shafts and at least one positioning element being aligned and positioned to receive therebetween a container end introduced into said interior from said entrance with a periphery of said container end engaged in said grooves of said shafts, such that rotation of said shafts causes said grooves to produce particles at said periphery while conveying said can end from said entrance to and through said exit from the enclosure.
 16. Apparatus for treating container ends to remove loose particles therefrom, comprising: at least three shafts, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around said shaft at an outer surface thereof; and a drive for rotating said shafts about said axes of rotation, said shafts being aligned and positioned to receive therebetween a container end entering said apparatus with a periphery of said container end engaged in said grooves of said shafts, such that rotation of said shafts causes said grooves to produce particles at said periphery while conveying said container end through said apparatus, wherein said apparatus includes a source of gas under pressure and at least one nozzle communicating with said source and positioned to direct a jet of said compressed gas onto said peripheries of said container ends to remove particles as said container ends are conveyed by said shafts.
 17. Apparatus for treating container ends to remove loose particles therefrom, comprising: at least three shafts, each shaft being rotatable about a longitudinal axis of rotation and each shaft having a helical groove extending around said shaft at an outer surface thereof; and a drive for rotating said shafts about said axes of rotation, said shafts being aligned and positioned to receive therebetween a container end entering said apparatus with a periphery of said container end engaged in said grooves of said shafts, such that rotation of said shafts causes said grooves to produce particles at said periphery while conveying said can end through said apparatus, wherein said apparatus includes at least one brush positioned to contact said peripheries of said container ends to remove said particles as said container ends are conveyed by said shafts.
 18. A method of treating container ends to remove loose particles therefrom prior to subsequent processing, which method comprises passing container ends having loose particles through an enclosed volume, engaging the container ends with at least one solid moving element, at least at peripheral edges of the container ends, to break off and remove said loose particles within the enclosed volume, removing accumulated particles from the enclosed volume for disposal, and removing the container ends from the enclosed volume for said subsequent processing.
 19. The method of claim 18, wherein said accumulated particles are removed by passing a current of a gas through said enclosed volume.
 20. The method of claim 18, wherein said peripheral edges of said container ends are brushed to remove said loose particles therefrom.
 21. The method of claim 18, wherein said peripheral edges of said container ends are impinged with gas jets to remove said loose particles therefrom.
 22. In a process for producing and utilizing container ends involving several mechanical handling stages, the improvement which comprises treating said container ends to release loose particles therefrom in an enclosed volume prior to a first of said mechanical handling stages, and removing said released loose particles from said enclosed volume for disposal at a location remote from said mechanical handling stages, thereby preventing contamination of said handling stages with said loose particles. 